1. Field of the Invention
The invention relates to information transmitting method and apparatus, information processing method and apparatus, information recording method and apparatus, and information recording and reproducing method and apparatus which are suitable for use in a system such that in BS (Broadcast Satellite) broadcast, for example, information of contents is distributed by using a time zone after the broadcast is finished at night and the information of the contents is stored into a storage unit and reproduced.
2. Description of the Related Arts
In digital BS broadcast, a plurality of programs are broadcasted by using a band of one transponder. Among the ordinary programs which are broadcasted by the digital BS broadcast, there is a program whose broadcasting time zone is limited to the daytime and whose broadcast is finished at night. Therefore, after the ordinary broadcast is finished at night, a space band is caused in the band of the transponder. There is, accordingly, considered a method of distributing contents by effectively using the space band of the transponder that is caused after the end of the broadcast at night as mentioned above.
That is, for example, eight transponders of a band of 30 Mbps are installed in a digital BS satellite. For example, programs of six channels in case of SDTV (Standard Definition Television) broadcast and programs of two channels in case of HDTV (High Definition Television) broadcast can be transmitted by one transponder. The ordinary broadcast is not performed in a time zone, for example, from 1:00 at night to 5:00 in the morning.
As mentioned above, for a time interval during which the space band is caused in the transponder after the end of the broadcast at night, broadcast for contents distribution is performed by using the space band of the transponder. Information of the contents is received by a receiver in each home and temporarily stored in a storage device such as a hard disk drive provided for the receiver in each home. The information of the contents is read out from the storage device in a reception terminal in each home and reproduced by a television receiver in each home.
By sending the information of the contents by using the space band of the transponder for the time interval during which the space band is caused in the transponder after the end of the broadcast at night and storing the contents information into the storage device in the reception terminal in each home as mentioned above, the contents information can be transmitted at a low cost by effectively using the space band of the transponder.
In such a system, however, since a transport stream of MPEG2 is recorded as it is into the storage device, it is difficult to perform a trick play such as cue/review or the like.
That is, according to a video packet of MPEG2, an I picture encoded in its frame (or field), a P picture encoded by using a previous frame (or field), and a B picture encoded by using previous and subsequent frames (or fields) are sent. It is necessary to use the I picture when the trick play such as cue/review or the like is performed. Therefore, in case of recording the MPEG2 video stream into the storage device as it is, when the trick play is performed, the video packet of the I picture has to be certainly reproduced.
Therefore, there is a method whereby a picture type is identified from a picture coding type described in a TS packet and, in case of the I picture, code mark bits are set and the number of code mark bits is counted and added as a code mark value into index information and recorded. With such a method, the I picture is reproduced from the index information and the trick play can be performed. In such an example, however, the picture type is identified from the picture coding type described in the TS packet and, if the picture coding type cannot be detected, it is difficult to perform the trick play. According to the system in which the contents is distributed by using the space band of the transponder when the space band is caused in the transponder after the end of the broadcast as mentioned above, a method of encrypting the stream in order to protect the contents is considered. If the stream has been encrypted, it is impossible to identify the I picture by analyzing the picture coding type as mentioned above.